Re: [PATCH v8 01/15] x86/boot: Place kernel_info at a fixed offset

Ard Biesheuvel
2024-08-28T17:45:22Z

(cc Stuart)

On Thu, 21 Mar 2024 at 15:46, Daniel P. Smith
<dpsmith@apertussolutions.com> wrote:
>
> Hi Ard!
>
> On 2/15/24 02:56, Ard Biesheuvel wrote:
> > On Wed, 14 Feb 2024 at 23:31, Ross Philipson <ross.philipson@oracle.com> wrote:
> >>
> >> From: Arvind Sankar <nivedita@alum.mit.edu>
> >>
> >> There are use cases for storing the offset of a symbol in kernel_info.
> >> For example, the trenchboot series [0] needs to store the offset of the
> >> Measured Launch Environment header in kernel_info.
> >>
> >
> > Why? Is this information consumed by the bootloader?
>
> Yes, the bootloader needs a standardized means to find the offset of the
> MLE header, which communicates a set of meta-data needed by the DCE in
> order to set up for and start the loaded kernel. Arm will also need to
> provide a similar metadata structure and alternative entry point (or a
> complete rewrite of the existing entry point), as the current Arm entry
> point is in direct conflict with Arm DRTM specification.
>

Digging up an old thread here: could you elaborate on this? What do
you mean by 'Arm entry point' and how does it conflict directly with
the Arm DRTM specification? The Linux/arm64 port predates that spec by
about 10 years, so I would expect the latter to take the former into
account. If that failed to happen, we should fix the spec while we
still can.

Thanks,
Ard.